Stereoscopic format converter

ABSTRACT

A device and method for converting one stereoscopic format into another. A software-enabled matrix is used to set forth predefined relationships between one type of format as an input image and another type of format as an output image. The matrix can then be used as a look-up table that defines a correspondence between input pixels and output pixels for the desired format conversion.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation application and claimspriority to co-pending U.S. patent application Ser. No. 10/613,866,filed Jul. 2, 2003 entitled “Stereoscopic format converter” which is anon-provisional application of and claims priority to U.S. ProvisionalPatent Application No. 60/393,605, filed Jul. 2, 2002 entitled“Stereoscopic format converter,” both of which are incorporated hereinby reference in their entirety as if set forth in full.

BACKGROUND OF THE INVENTION

With the rise of electronic stereoscopy in the last two decades,different formats have been used to produce stereoscopic images. Thesubject is discussed in Lipton's paper in the 1997 SPIE ProceedingsStereoscopic Displays and Virtual Reality Systems IV volume 3012entitled Stereovision Formats For Video And Computer Graphics. Theformats sometimes involve means for producing a sequence of fields, andrequire selection devices employing electro-optical shutters foroccluding and passing fields. In this way each eye of the viewer seesits appropriate perspective view. In some cases, the parts of theelectro-optical system are distributed, covering the monitor with amodulator and passive eyewear at the eyes of the beholder.

Many formats come down to the same thing—an alternating sequence of leftand right fields. Also common is page flipping, which requires astereo-ready video graphics board that can accept the proper calls from,typically, an open GL application, which can then signify or index theappropriate field so that each eye sees its appropriate image. Othermeans have been created in addition to the page-flipping mode, which isone that is common on UNIX workstations but less common on Windowsworkstations. The above/below format (sometimes called sync doubling)invented by Lipton et al. is a format that is not board dependent, asdescribed in U.S. Pat. No. 4,523,226, entitled Stereoscopic TelevisionSystem. This is a commonly used technique, but it does not allowstereoscopic windows to be produced, and it has other disadvantages,although it will function without regard to the video board used.

Another approach, the interlace approach, uses alternating fieldsrunning at the usual repetition rate, for example, 60 or 70 fields persecond, and thereby produces a flickering image. This is a method thathas been used for video systems, and it can be used for DVD encoding ofstereo images as described in co-pending and commonly assigned U.S.application Ser. No. 10/150,595 entitled Plano-Stereoscopic DVD Movies.

Another method, the interline method, writes left and right lines on thesame video field and squelches them using a “dongle” which connects tothe VGA video port of the computer. In this way, left and right imagesare passed at the discretion of the dongle, which alternately squelchesleft and right lines.

There are some people (children especially) who are perfectly contentwith the redoubtable anaglyph which uses color encoding of the left andright images. This method was described almost a century-and-a-half agoand is most often used with red and green or red and blue filters. Thereare two major variants. One is a polychrome anaglyph that attempts togive some semblance of color. The other is a more traditional monochromeanaglyph that is probably more pleasant for most people to look at, butlacks the pizzazz of having a color effect.

CRT monitors allow for field-sequential or alternate field stereoscopicdisplays (described above), whereas liquid crystal displays do notbecause of image lag. In order to see a stereo image on a liquid crystaldisplay, the anaglyph is required. Another method for use on such anuncooperative monitor would be to place the left and right images sideby side, in which case they can be free viewed (no selection device) bypeople who have the knack. There's also the possibility of usinglorgnettes, or eyewear that have prisms in them, so that the images canbe converged for the observer.

StereoGraphics Corp. of San Rafael, Calif., sells SynthaGram®autostereoscopic monitors which use a special multi-tile format; yetanother format variation to be reckoned with.

This disclosure addresses material that is produced in one format andthen disseminated to users without knowledge of the user's hardware orits ability to play back the image. For example, an above-and-belowformatted image might be sent to someone who has a laptop with abuilt-in liquid crystal display screen. Can he/she view the stereoimage? Generally no—unless, for example, the image can be transformedinto an anaglyph which is independent of the display's ability torefresh at a given rate without fields blending into each other.

In general, there are a wide variety of formats and many kinds of PC'sand monitors in use and not a high degree of certainty that a user willbe able to view stereoscopically in the format received.

In addition, there are people who would like to see stereoscopic imagesbut who have planar stills or movies to look at. These people mightenjoy seeing a stereoscopic image for the novelty's sake. Even if itisn't a true stereoscopic image, it might be pleasant, in somecircumstances, to provide an ersatz stereoscopic image.

SUMMARY OF THE INVENTION

A device and method for converting one stereoscopic format into anotheris disclosed. In addition, a method for creating ersatz stereo images isdisclosed. In general, an input image and an output image are eachdefined by a plurality of pixels. According to the invention, asoftware-enabled matrix is used to set forth predefined relationshipsbetween one type of format as an input image and another type of formatas an output image. More specifically, the matrix is a look-up tablethat defines a correspondence between input pixels and output pixels forthe desired format conversion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a block diagram showing a stereoscopic content converter.

FIG. 1B illustrates several types of conventional source formatstypically used as inputs for the stereoscopic content converter.

FIG. 1C illustrates various display techniques provided as outputs bythe stereoscopic content converter.

FIG. 2 is a diagram showing a source/display matrix for the stereoscopiccontent converter.

FIG. 3 is a diagram of a single source/display matrix cell.

FIG. 4 is a block diagram of a pipeline for the stereoscopic contentconverter.

FIG. 5 is a diagram of a mapping technique used in the stereoscopiccontent converter.

FIG. 6 is a diagram illustrating identity mapping for the stereoscopiccontent converter.

FIG. 7 is a diagram of the stereoscopic pipeline having a multistage.

FIG. 8 is a diagram that illustrates a shifting method to stereo-ize animage.

FIG. 9 is a diagram that illustrates a skewing method to stereo-ize animage.

FIG. 10 is a diagram that illustrates a method for handlingstereo-pairs.

FIG. 11 is an illustration of how a viewer uses a view-alignment stripto properly locate his/her head with respect to the display screen.

FIG. 12 is an illustration of the construction of the view-alignmentstrip.

DESCRIPTION OF THE INVENTION

FIG. 1A shows a stereoscopic content converter 10. The stereoscopiccontent converter is a software-enabled utility that converts imagesfrom one format to another. FIG. 1A also shows exemplary formats thatmay be inputted and outputted. Thus, the stereoscopic content converter10 is able to take any one of a wide variety of different image formatsand play them back on many different kinds of PC's and display screens.Another advantageous feature is the capability to “stereo-ize” a planarstill or movie image. The means for accomplishing this and other aspectsof the invention are set forth below.

The content player 10 handles two basic forms of digital content—stillimages and movies. For simplicity, this description assumes a movie is aseries of still image frames and does not consider intermediatecompression, headers, or other storage details that are routinelyhandled by the software media framework. It is assumed that all data isdigital, either created by means of a photographic film process andlater digitized, or directly captured or authored in a digital form. Ascurrently implemented and tested, the stereoscopic content converter 10is able to run on a number of Windows Operating Systems and read in abroad selection of contemporary file formats. However, it would be aroutine matter for a programmer to convert the application to run on adifferent operating system.

There are numerous conventional media frameworks available today toallow an application to process movie data. Typical processing stepsinclude opening, starting, stopping, pausing and seeking. The preferredframework used in the present implementation of the stereoscopic contentconverter 10 is Microsoft's DirectShow (a component of Microsoft'sDirect X technology). Other frameworks, such as Apple's Quick TimePlayer, could also be used. Although typically used in the context ofmovie data, media frameworks can also handle still image data as well.

A user interface is provided for the converter 10 and preferablyincludes a set of VCR-like controls for manipulating the video—start,stop, pause, rewind and fast forward. The user can also adjust thespeed, volume control, and balance. The converter can provide visualcontrol feedback in the interface to allow the user to precisely adjustthese settings. As with most modern media viewers, the stereoscopiccontent converter 10 is configured to allow a user to view content inboth windowed and full screen display modes.

This media content is opened by the stereoscopic content converter 10and displayed to a user. In its current implementation, the converter 10is used as a real-time format converter. No storage of the displayedcontent is provided. It is an obvious extension to provide for this, butbecause of extensive output disk operations, this would typicallycompromise the playback speed performance.

The word “Source” as used herein refers to the input format of themedia. An illustration of the various potential source formats that aversatile software stereo player should be able to handle is shown inFIG. 1B. It is not a complete listing, but diverse enough to show thevariation existing in the art. Note that there are some establishedconventions as to how left and right data are stored. Also, a squareaspect ratio is shown to illustrate the scaling of the frames within thesource format.

The following is a guide to understanding FIG. 1B:

Planar: A non-stereo image.

Above/below: Two vertically squashed stereo images with the right imageon top of the left image.

Side-by-side: Two full size images with the right image on the leftside.

Side-by-side Squashed: Two horizontally squashed image pairs with theright image on the left side.

Interline: Two horizontally squashed image pairs interwoven, with thefirst line containing the first line from the right image, the secondline containing the first line from the left image, the third linecontaining the second line from the right image, and so forth.

Interlace: Relies on using the odd and even fields of a video image todisplay left and right (or right and left) images.

Stereo pair: Two full size images, one left and one right.

Nine Tile: Nine ⅓ sized stereo images stored in a 3×3 grid. The upperleft image is the far left image and the lower right is the far rightimage. This format is used for StereoGraphics' SynthaGram® monitor.

Stereo-ize: Two stereo synthesized full size images, one left and oneright.

Interzigged image: A full size image comprising an optically formedpattern of 9 stereo images. This format is used for StereoGraphics'SynthaGram® monitor.

Anaglyph: A full size image comprising a red/blue colored image fromstereo pairs.

The word “Display” refers the output technique used to present thestereo content to the user. An illustration of the various potentialdisplays that a versatile software stereo player should be able tohandle is shown in FIG. 1C. Again, it is not a complete list, butdiverse enough to show the variation existing in the art. Also, a squareaspect ratio is shown to illustrate the scaling of the frames in thedisplay

The following is a guide to understanding FIG. 1C:

Left view: The left view of a stereo pair.

Right view: The right view of a stereo pair.

Free viewing: Both left and right views shown together, with the left onthe left side and the right on the right side.

Page flipped: The left and right views shown alternatively by means of agraphics card flipping operation, with the flipping occurring insequence with synchronized active shuttering eyewear.

Sync doubled: The left and right views shown alternatively by means of avideo signal modifier, which introduces vertical sync pulses betweenartificially created sub-fields. Shuttering eyewear are synchronizedwith the resultant field sequential images displayed on an appropriatemonitor. The term sync doubled is synonymous with the above/belowformat.

SynthaGram: Nine views are shown together by means of a specialoptically designed autostereo monitor requiring no eyewear.

Anaglyph—monochromatic: Left and Right view intensity information storedin the color channels and viewed with red/blue-filtered eyewear.

Anaglyph—polychromatic: Left and Right view color information stored inthe color channels and viewed with red/blue filtered passive eyewear.

As illustrated in FIG. 2, a matrix 20 can be formed with the sourceformats along the vertical axis and the display methods along thehorizontal axis. Each element 21 of the matrix 20, as shown in FIG. 3,can contain the following information: 1) whether that combination ispossible to produce, and 2) whether that combination is supported in theviewer. Several stereo source formats are either fully or partiallyirreversible to the original left, right image pairs. In some cases, theresulting images are scaled up, or have lost color information, or aresimply not possible to reconstruct. For example, showing the right viewof an anaglyph source results in a gray scale image with the colorinformation being lost. Another example is showing the right view of aside-by-side horizontally squeezed source that must result in a scaledimage.

All of this information is enumerated into a support matrix table 20,which can be software enabled in the stereoscopic content converter 10.Aside from properly handling the scaling aspects, this table 20 is usedto prevent invalid combinations from being available and selectable bythe user.

Given any single supported combination of source and display selections,a hardcoded geometric based transformation can be developed and used ina specialized software application. Although this approach would bequite efficient, it is limited to that particular combination.

To support the more generic approach to many combinations of source anddisplay selections, a generalized processing pipeline has beendeveloped. This pipeline contains well-defined processing stages thathandle an input frame and move it along on its way to eventually beingdisplayed to the user. The input frame is either a single frame in amovie file or an individual image file. In this model, the output of onestage is taken as the input of the next stage. If a stage is notrequired, the output is efficiently passed through onto the next stage.

A tradeoff between processing speed and accuracy needs to be taken intoaccount. In many cases, exact scaling or color handling is not nearly ascritical as the ability to play at a predefined frame rate. Also, theability to leverage the specialized graphics processing power in currentvideo cards is important to achieve. Rather than designing for the leastcapable graphics card, a scheme of querying for supported capability isused.

For this implementation of the above mentioned source formats, a maximumof nine stereo views is required. This is not a rigid requirement, andthe implementation can be easily expanded to handle stereo solutionsrequiring more views.

These stages are set up ahead of time so that processing of animationframes can be done as efficiently as possible. A small performance hitis taken every time the source/display combination is changed. However,during a movie playback, the processing of each frame is made asefficient as possible. These stages are illustrated in FIG. 4 anddescribed below:

Stage 1—Color Space Conversion 51: A uniform color space is neededthroughout the pipeline. In a preferred implementation, the color spacechosen is a R8G8B8, where each Red, Green, and Blue component is definedas one byte each.

Stage 2—Software Scaling 52: The frame is symmetrically scaled to a tolarger or smaller size. Although various averaging techniques (e.g.bilinear filtering) can be implemented, for efficient mapping processing(described below), a simpler scheme was implemented. For each outputpixel in the scaled frame, the single closest input pixel is chosen.

The software scale factor used is the same horizontally and vertically.The value of the scale factor is determined by the specificsource/display combination, the size of the output window, and whetherthe graphics card can perform scaling.

Many graphics cards are capable of efficiently doing image scaling as afinal step before presenting the image on the screen. However to takeadvantage of that feature, all scaling needs to be deferred until thelast stage.

Stage 3—Inversion 53: Based on some image formats, the frame may need tobe inverted so that the bottom line becomes the top line. In some cases,this is required because the media framework inverts, in other cases,the output graphics system convention requires it.

Stage 4—Views 54: The objective of this stage is to create the variousstereo views that will be needed later in the pipeline. Depending on thesource/display combination—one, two or nine views may be needed. Theseviews can be easily extracted in a geometric manner from the input ofthe previous stage. The special case of stereo-izing is discussed below.

Stage 5—Alignment 55: For correct stereo viewing, the views may need tobe aligned in a horizontal or vertical direction, or even rotational.Allowing for alignment gives the user an easy tool to compensate for illformed stereo views. This calculation is a simple shifting (or rotating)of the views, replacing lost pixels with black ones. Pixel units used indefining the shifting must correlate to final screen units. Hence, nohardware scaling is done when an alignment is to occur.

Stage 6—Swapping 56: The need to swap views is an inherent requirementwhen viewing stereo media. At various points during the creation toviewing of stereo images, there lies the opportunity to introduce anunwanted swap of the left/right pair. During this stage, either the twoviews are swapped (views 1,2 become views 2,1) or all nine views areswapped (views 1,2,3,4,5,6,7,8,9 become views 9,8,7,6,5,4,3,2,1).

Stage 7—Pre-Interzig 57: This stage is required for SynthaGram®Autostereo displays, which require an optically defined arrangement ofpixels created by an “interzigging” process. To prepare for thisinterzigging operation, a predefined view arrangement needs to be setup. This arrangement is equivalent to the nine tile source formatdescribed above where a single frame contains nine tiles, each tilecontaining a scaled down version of one of the nine views. Two views canalso be supported in this format by duplicating the views in the ninetile arrangement (e.g. View 1 is used in Tiles 1-4 and View 2 is used inTiles 5-9). If no interzigging is to be performed, this stage is passedthrough.

Stage 8—Interzig 58: The algorithm used to interzig may be considered ablack box and hence hidden to the application. The interzig algorithmmay be accessed through various software methods including a singlefunction call. Depending on the model of autostereo monitor used, adifferent algorithm or the same algorithm with different parameters isused. Using the pixel arrangement set up in the previous stage, theinterzigging operation is now performed. The result is an interziggedimage, which is viewable on a SynthaGram monitor. Because of the precisearrangement of views stored in the pixels, interzigged images can not bescaled. If no interzigging is to be performed, this stage is passedthrough.

Stage 9—Presentation 59: The image now needs to be prepared on apresentation area that corresponds to the particular display method.This presentation represents the image that the user will eventually seeon the screen. This stage is either a simple copy of the previous stage,or involves combining several views for the presentation. One example isthat in the case of a sync-doubled display, both the left and rightviews are combined in a single presentation. Another example is that foran anaglyph representation, color components from both the left andright pixel views are combined. A to third example is that for apage-flipped display, two presentations (one for each view) are requiredto be constructed.

Stage 10—Centering 60: The presentation needs to be properly placed sothat it appears centered to the user. This stage looks at the size ofthe display window (or full screen dimensions) and centers thepresentation. For some displays (such as the SynthaGram), correctplacement of the image relative to the monitor is critical to achieve abalanced viewing effect of the stereo images.

Stage 11—Device Format 61: Up until now, the previous stages have used apredefined color space. In this stage, the presentation is converted tothe color format used by the graphics display. For some displaytechniques, such as those using OpenGL libraries, this stage isperformed transparently in graphics libraries. In other cases, aconversion to a specific color space is needed (e.g. R8G8B8 to R5G6B6 orR8G8B8 to R8G8B8A8). This conversion typically involves rearranging thecomponents, adding an alpha component, quantizing components from 8 bitsto 6 bits, and reorganizing components into a different number of bytes.

Stage 12—Display 62: In this stage, the image is actually displayed tothe user using one of several display techniques including pageflipping. Hardware scaling of the image may occur here as well.

If each frame of an animation is processed Using these stages, thecorrect display will result—however, the processing performance will bequite slow. A mapping technique can be employed to efficiently combinemost of these stages into a single operation.

Each stage represents a transformation from an input image space to anoutput image space. A map can be defined as shown in FIG. 5, whichdescribes for each output pixel component the proper pixel component inthe input image space to use. Mapping requires that no combining ormixing of pixels be allowed; however, it allows for the input and outputspaces to be different dimensions. For a stage that is simply passedthrough, an identity map, as shown in FIG. 6, can be set up. Also,because these maps are defined on a component basis (rather than a pixelbasis), they need to be defined in terms of a consistent pixel format(e.g. R8G8B8).

The following maps can now be defined:

Stage 1 Map: Color Space Conversion to input frame

Stage 2 Map: Software Scaled to Color Space Conversion

Stage 3 Map: Inversion to Software Scaled

Stage 4 Map(s): Views to Inversion

Stage 5 Map(s): Aligned Views to Views

Stage 6 Map(s): Swapped Views to Aligned Views

Stage 7 Map: Pre-Interzig to Swapped Views

Stage 8 Map: Interzig to Pre-Interzig

Stage 9 Map: Presentation to Interzig

Stage 10 Map: Centering to Presentation

Stages 11 and 12 cannot be handled in the same pixel format, so no mapis created for them.

Once these maps are defined, it is a greatly efficient step toconcatenate them, creating a single multistage map 65 for performing allten stages, as shown in FIG. 7. This greatly simplifies the pipeline.Given an input image, the centered image can be constructed by simplyusing the multistage map and looking up each pixel component in theinput image. This is a critical performance step and having at most oneoperation per pixel component is optimal.

We will now describe what we call the “Stereo-ize” function. A user maydesire to create stereo image pairs from a single planar source that hasbeen created with no stereo information. The stereoscopic contentconverter 10 uses two methods to synthesize these pairs, both of whichare congruent with the mapping approach described above. These methodsare simplistic approximations to a more difficult problem of accuratelysynthesizing stereo views by analyzing structure within the sourceimage. These approximations are based on simple 3D rotations of thesource image to create a second image. Using the original source imageand the created second image together gives an implied stereo effect.This technique is also well-suited for the stereoscopic contentconverter architecture.

The first method, “Shifting”, as shown in FIG. 8, involves the followingsteps:

a) Symmetrically scaling the image by a fixed percentage as shown instep 70. We have found that 4% works well for many images. Consider thisscaled image to be the scaled left image.

b) Make a copy of the scaled left image to create a scaled right imageas shown in step 71.

c) Shift the scaled right image by half of the scaling percentage, asshown in step 72. Ignore any pixels “lost” and “gained” during theshifting.

d) Extract a centered image of the original image size from the scaledleft image, as shown in step 73. This is the stereo-ized left image.

e) Extract a centered image of the original image size from theshifted/scaled right image, as shown in step 74. This is the stereo-izedright image.

The second method, “Skewing”, as shown in FIG. 9, involves the followingsteps:

a) Symmetrically scaling the image by a fixed percentage, as shown instep 70. We have found that 4% works well for many images. Consider thisscaled image to be the scaled left image.

b) Make a copy of the scaled left image to create a scaled right image,as shown in step 71.

c) Skew the scaled right image by half of the scaling percentage, asshown in step 82. Ignore any pixels “lost” and “gained” during theshifting.

d) Extract a centered image of the original image size from the scaledleft image, as shown in step 73. This is the stereo-ized left image.

e) Extract a centered image of the original image size from theshifted/scaled right image, as shown in step 74. This is the stereo-izedright image.

Although the scaling/skewing percentage is preferably fixed in thestereoscopic content converter 10, it is an obvious extension to allowthe user to define the percentage. Also, as shown in FIGS. 8 and 9, bothmethods are a subset of an infinite number of directions to apply ashift and skew. Hence, it is also an obvious extension to allow the userto specify the direction of the stereo effect and its magnitude.

Implementing these methods in the staged pipeline described above isstraightforward. Steps a and b are performed in the software scalingstage. Steps c, d, and c are performed in the view stage.

The Shifting method is known in the prior art and has been implementedby inventors and manufacturers on many occasions. It is a directoutgrowth of experiments done more than a century ago that establishedthat horizontal shifting of one image of a stereo pair can move theentire image away from the observer.

The Skewing method provides an ersatz stereo effect and is based on aprior art method that was disclosed as a hardware implementation.Skewing, as described here, is produced by software or algorithmic meansdescribed above to slope, the image as if it were projected on areceding plane whose front is the lower horizontal edge of the picture,and whose far edge is at the top. M. Weiner, in U.S. Pat. No. 3,339,454,first described the method of slanting or sloping a planar photo orprojected image and placing it behind a frame through which it might beviewed. Weiner sought to approximate stereoscopic depth by this means.He reasoned that typical scenes have the lower portion closer to theobserver than the top portion of the scene. (Shanks, in U.S. Pat. No.4,441,565 discusses a similar method but relies on projecting a planarimage on a saddle shaped curve or surface.)

Parallax will be generated using this slanted or tipped image, but theparallax is only associated with the sloped plane of the screen ratherthan with an image specific set of homologous points contained within aconventional stereo pair. The addition of the frame is an ingenioustouch and provides a means for comparing the depth of the receding imagewith the frame. The surrounding computer screen serves the same functionas Weiner's frame, and provides a reference for the ersatz stereo imageformed by the stereoscopic content converter 10.

Skewing is also of interest because, unlike other methods that have beenproposed for ersatz stereo, this one can be computed on the fly,virtually in real time. Therefore, no preprocessing of the image isrequired. The effect tests remarkably well. For many individuals thereis little distinguishable difference between a skewed image and a truestereo image.

The content converter 10 also performs a unique and interesting processthat we call anaglyph deconstruction (and reconstruction). In thisprocess, an anaglyph, as an inputted format, is outputted as one of theother formats. For example, an anaglyph may be deconstructed and turnedinto the above/below format or the page flipped format for display on aCRT monitor for use with shuttering eyewear. Thus, the user is able toview and evaluate an image stereoscopically, but without the eye fatigueassociated with the anaglyph. In this case, the image no longer hascomplimentary color components. Instead, the stereo pair is made up oftwo monochromatic components that are easier to view for most people.

A special case is created for handling stereo image pairs, i.e., a setof two individual files. The pipeline as well as the media framework isoptimized for handling a single media file at a time. As shown in FIG.10, the stereoscopic content converter handles a pair of stereo files90, 91 by reading each file independently as a planar source and thenobtaining an in-memory copy of each file. A temporary file is thenconstructed defining a combined image, with the left file 92 stored ontop and the right file 93 stored on bottom. This single image format isunderstood in the stereoscopic content converter 10 and the pipeline asa “stereo pair” and is easily processed.

Because of the lack of support in the media framework for simultaneouslyplaying multiple files, stereo movie pairs are not currently supported.It would be a straightforward task to develop a utility program orutilize a video-editing program (such as Adobe Premiere) to combine leftand right movies into a single movie with left and right content in eachframe.

Viewing content on the SynthaGram autostereo monitor requires the userto stay in a relatively small viewing zone. This zone is easy to findwhen viewing some content (e.g. test images), but more difficult whenviewing other types of content. We have experimented with sometechniques and discovered that a properly formatted view alignment strip102 located at the top of the displayed frame 100, as shown in FIG. 11,works well in this task. The strip 102 is designed such that a yellowstrip appears brightest when viewed from a central location. Whenviewing content on the SynthaGram monitor, a user simply has to firstposition him/herself so that the strip 102 shows the yellow stripbrightly, and then move his/her eyes down slightly to correctly view thecontent.

The strip 102 is constructed using the same SynthaGram settings that thecontent is formatted with. As shown in FIG. 12, a series of an oddnumber of views 110 are used with the center view 112 containing yellowpixels and the other pixels containing black pixels. The views 110 havea narrow aspect ratio (⅓ window width×8 lines). The views 110 are theninterzigged in block 114 using the proper settings for the monitor. Theresulting strip 102 (window width×24 lines) is then composited on top ofthe displayed window.

We have described a series of methods for converting from one stereoformat to another. We have crafted our method to be compatible with theubiquitous Windows operating system, but obviously it is not limited toWindows. We have also described simple for producing an ersatz stereoimage from a planar image. Although the present invention has beendescribed with reference to specific exemplary embodiments, it will beevident that various modifications and changes may be made to theseembodiments without departing from the broader spirit and scope of theinvention. Accordingly, the specification and drawings are to beregarded in an illustrative rather than a restrictive sense. Thus, withregard to the claims appended to this application, the full range ofscope afforded by the language of these claims is not to be limited byany of the embodiments set forth above.

The invention claimed is:
 1. A method of format conversion comprising:receiving input image data having an input image format; providingoutput image data for displaying an output image on a display, theoutput image data having a stereoscopic output format; determiningwhether the input image format can be converted to the stereoscopicoutput format; and converting the input image format to the stereoscopicoutput format only if it is determined that the input image format canbe converted to the stereoscopic output format; wherein the convertingis performed according to a predefined relationship between the inputimage format and the stereoscopic output format, and wherein the inputimage format and the stereoscopic output format are different.
 2. Themethod of claim 1, wherein the processing comprises accessing a supportmatrix table that sets forth the predefined relationship between theinput format and the stereoscopic output format.
 3. The method of claim2, wherein the support matrix table comprises software instructionsexecutable by a processor.
 4. The method of claim 1, wherein theprocessing comprises converting each pixel component of the input imageformat to at least one pixel component of the stereoscopic outputformat.
 5. The method of claim 1, wherein the processing comprises usinga map to convert each pixel component of the input image format to onepixel component of the stereoscopic output format.
 6. The method ofclaim 1, further comprising creating the output image based on theoutput image data.
 7. The method of claim 6, further comprisingdisplaying the output image on the display.
 8. The method of claim 6,wherein the processing further comprises an action selected from thegroup consisting of: converting the color space of the input imageformat; scaling the input image format; creating additional views;swapping views; preparing a presentation of the output image; centeringthe presentation; and formatting the presentation.
 9. The method ofclaim 8, wherein all of the converting of the color space, the scalingof the input image format, the creating of additional views, theswapping of views, the preparing of a presentation, the centering of thepresentation, and the formatting of the presentation are performed, andwherein all of those action are performed in sequential order.
 10. Themethod of claim 9, further comprising inverting the input image formatafter the scaling action and before the creating of additional views.11. The method of claim 9, further comprising aligning the views afterthe creating of additional views and before the swapping action.
 12. Themethod of claim 8, further comprising: arranging a predefined viewwherein a single frame contains a plurality of views; and interziggingthe views.
 13. The method of claim 1, wherein the input image format isassociated with a planar image, the method further comprising creating astereo image pair from the planar image.
 14. The method of claim 13,wherein the creating of the stereo image pair comprises: scaling theplanar image by a fixed percentage to create a scaled image; copying thescaled image to create a complimentary image; shifting the complimentaryimage by a smaller percentage of the fixed percentage; extracting acentered image from the scaled image; and extracting a centered imagefrom the shifted complimentary image.
 15. The method of claim 14,wherein the smaller percentage is 50%.
 16. The method of claim 13,wherein the creating of the stereo image pair comprises: scaling theplanar image by a fixed percentage to create a scaled image; copying thescaled image to create a complimentary image; skewing the complimentaryimage; extracting a centered image from the scaled image; and extractinga centered image from the skewed complimentary image.
 17. The method ofclaim 16, wherein the complimentary image is skewed by 50%.
 18. Themethod of claim 1, wherein the input image data has a plurality of inputimage formats, and the determining comprises determining whetherconversions of the input image formats to the stereoscopic output formatare supported.
 19. The method of claim 18, wherein the plurality ofinput image formats comprise stereoscopic input image formats.
 20. Themethod of claim 1, wherein the determining comprises determining whetherthe conversion of the input image format to one of a plurality of thestereoscopic output formats is supported.
 21. A method of formatconversion comprising: receiving, at a processor, input image datahaving an input image format; providing, from the processor, outputimage data for displaying an output image on a display, the output imagedata having a stereoscopic output format; determining whether the inputimage format can be converted to the stereoscopic output format; andconverting, with the processor, the input image format to thestereoscopic output format only if it is determined that the input imageformat can be converted to the stereoscopic output format; wherein theconverting is performed according to a predefined relationship betweenthe input image format and the stereoscopic output format, and whereinthe input image format and the stereoscopic output format are different.22. A method of format conversion comprising: receiving input image datahaving an input image format; providing, from a processor, output imagedata for displaying an output image on a display, the output image datahaving a stereoscopic output format; determining whether the input imageformat can be converted to the stereoscopic output format; andconverting, with the processor, the input image format to thestereoscopic output format only if it is determined that the input imageformat can be converted to the stereoscopic output format; wherein theconverting is performed according to a predefined relationship betweenthe input image format and the stereoscopic output format and isexecuted in a processing pipeline, the pipeline comprising a pluralityof processing stages; and wherein the input image format and thestereoscopic output format are different.
 23. The method of formatconversion of claim 22, wherein the converting in the processingpipeline is executed in sequence.
 24. A method of format conversioncomprising: receiving input image data having an input image format;providing output image data for displaying an output image on a display,the output image data having a stereoscopic output format; determiningwhether the input image format can be converted to the stereoscopicoutput format; and converting the input image format to the stereoscopicoutput format if it is determined that the input image format can beconverted to the stereoscopic output format; wherein the converting isperformed according to a predefined relationship between the input imageformat and the stereoscopic output format, and wherein the input imageformat and the stereoscopic output format are different.